email domain association decommisioning

I was the administrator of our Zoom subscription and I found out that our subscription was not continued by management. I was not informed and now I get helpdesk calls from users who want to participate with other companies zoom meetings and they cannot register due to our associated domain registration.

I cannot delete or administer the registration any more and I filed a case a few days agoo, but no response from support still.  

How do I contact zoom support to finally end that domain registration?